Cavity lock system for a blowout preventer

ABSTRACT

A blowout preventer (BOP) includes a ram supported within a cavity that is positioned crosswise to a central bore of the BOP. The ram is configured to move within the cavity between an open position in which the ram is withdrawn from the central bore and a closed position in which the ram is positioned within the central bore to thereby block a fluid flow through the central bore. The BOP also include a lock member that is configured to move between an unlocked position and a locked position in which the lock member is positioned within the cavity of the BOP and contacts the ram to thereby lock the ram in the closed position.

BACKGROUND

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

A blowout preventer (BOP) stack is installed on a wellhead to seal and control an oil and gas well during drilling operations. A drill string may be suspended inside a drilling riser from a rig through the BOP stack into the wellbore. During drilling operations, a drilling fluid is delivered through the drill string and returned up through an annulus between the drill string and a casing that lines the wellbore. In the event of a rapid invasion of formation fluid in the annulus, commonly known as a “kick,” a movable component within the BOP stack may be actuated to seal the annulus and to control fluid pressure in the wellbore, thereby protecting well equipment disposed above the BOP stack.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying figures in which like characters represent like parts throughout the figures, wherein:

FIG. 1 is a block diagram of a mineral extraction system, in accordance with an embodiment of the present disclosure;

FIG. 2 is cross-sectional side view of an embodiment of a BOP that may be used in the system of FIG. 1, wherein a ram is withdrawn from a central bore of the BOP and a lock member is withdrawn from a cavity of the BOP;

FIG. 3 is a cross-sectional side view of the BOP of FIG. 2, wherein the ram is within the central bore of the BOP and the lock member is within the cavity of the BOP to lock the ram within the central bore of the BOP;

FIG. 4 is a cross-sectional side view of an embodiment of a portion of a BOP that may be used in the system of FIG. 1, wherein a ram is withdrawn from a central bore of the BOP and is configured to hold a lock member in a first lock position;

FIG. 5 is a cross-sectional side view of the portion of the BOP of FIG. 6, wherein the ram is within the central bore of the BOP and the lock member is in a second lock position to lock the ram within the central bore of the BOP;

FIG. 6 is a cross-sectional side view of an embodiment of a portion of a BOP that may be used in the system of FIG. 1, wherein a ram is withdrawn from a central bore of the BOP, a lock member is withdrawn from a cavity of the BOP, and the lock member is configured to rotate relative to the ram;

FIG. 7 is a cross-sectional side view of the portion of the BOP of FIG. 6, wherein the ram is within the central bore of the BOP and the lock is within the cavity of the BOP to lock the ram within the central bore of the BOP;

FIG. 8 is a cross-sectional side view of an embodiment of a portion of a BOP that may be used in the system of FIG. 1, wherein a ram is within a central bore of the BOP, a lock member is within a cavity of the BOP, and the lock member is configured to move at a non-perpendicular angle relative to the ram;

FIG. 9 is a cross-sectional side view of an embodiment of a portion of a BOP that may be used in the system of FIG. 1, wherein a ram is within a central bore of the BOP, a lock member is within a cavity of the BOP, and the lock member has a wedge shape;

FIG. 10 is a cross-sectional side view of an embodiment of a portion of a BOP that may be used in the system of FIG. 1, wherein a ram is within a central bore of the BOP, a lock member is within a cavity of the BOP, and the lock member has a wedge shape and the ram has a corresponding wedge shape;

FIG. 11 is a cross-sectional side view of an embodiment of a portion of a BOP that may be used in the system of FIG. 1, wherein a ram is within a central bore of the BOP, a lock member is within a cavity of the BOP, and the lock member is configured to engage a connecting rod to lock the ram within the central bore of the BOP; and

FIG. 12 is a flow diagram of an embodiment of a method of operating a cavity lock system for a BOP that may be used in the system of FIG. 1.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present disclosure will be described below. These described embodiments are only exemplary of the present disclosure. Additionally, in an effort to provide a concise description of these exemplary embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

The present embodiments are generally directed to blowout preventers (BOPs). In particular, the present embodiments are generally directed to BOPs that include a cavity lock system that includes one or more lock members that are configured to extend into a cavity (e.g., ram cavity) of the BOP to contact and/or to block movement of one or more rams of the BOP. For example, each ram may be configured to adjust from a first ram position (e.g., open position) in which the ram is withdrawn from a central bore of the BOP to a second ram position (e.g., closed position) in which the ram is positioned within the central bore of the BOP. Each lock member may be configured to adjust from a first lock position (e.g., unlocked position or configuration) in which the lock member does not block movement of the ram to a second lock position (e.g., locked position or configuration) in which the lock member is positioned within the cavity of the BOP to contact and/or to lock the ram in the second ram position (e.g., to block the movement of the ram from the second ram position to the first ram position; to block withdrawal of the ram from the central bore). Advantageously, the cavity lock system may be a compact lock system (e.g., due to its position at the cavity that houses the ram) that is operable to lock each ram of the BOP in the second ram position and to thereby maintain the BOP in a closed configuration to block a fluid flow through the central bore of the BOP.

While the disclosed embodiments are described in the context of a drilling system and drilling operations to facilitate discussion, it should be appreciated that the BOP may be adapted for use in other contexts and other operations. For example, the BOP may be used in a pressure control equipment (PCE) stack that is coupled to and/or positioned vertically above a wellhead during various intervention operations (e.g., inspection or service operations), such as wireline operations in which a tool supported on a wireline is lowered through the PCE stack to enable inspection and/or maintenance of a well. In such cases, the BOP may be adjusted from an open configuration to the closed configuration (e.g., to seal about the wireline extending through the PCE stack) to isolate the environment, as well as other surface equipment, from pressurized fluid within the well. In the present disclosure, a conduit may be any of a variety of tubular or cylindrical structures, such as a drill string, wireline, Streamline™, slickline, coiled tubing, or other spoolable rod.

With the foregoing in mind, FIG. 1 is a block diagram of an embodiment of a mineral extraction system 10. The mineral extraction system 10 may be configured to extract various minerals and natural resources, including hydrocarbons (e.g., oil and/or natural gas), from the earth, or to inject substances into the earth. The mineral extraction system 10 may be a land-based system (e.g., a surface system) or an offshore system (e.g., an offshore platform system). A BOP assembly 16 is mounted to a wellhead 18, which is coupled to a mineral deposit via a wellbore 26. The wellhead 18 may include any of a variety of other components, such as a spool, a hanger, and a “Christmas” tree. The wellhead 18 may return drilling fluid or mud to the surface 12 during drilling operations, for example. Downhole operations are carried out by a conduit 24 that extends through the BOP assembly 16, through the wellhead 18, and into the wellbore 26.

To facilitate discussion, the BOP assembly 16 and its components may be described with reference to a vertical axis or direction 30, a longitudinal axis or direction 32, and a lateral axis or direction 34. The BOP assembly 16 may include one or more BOPs 42 (e.g., 1, 2, 3, 4, 5, 6, 7, 8 or more ram BOPs) stacked relative to one another. A central bore 44 (e.g., flow bore) extends through the one or more BOPs 42. As discussed in more detail below, at least one of the BOPs 42 may include a cavity lock system that is configured to lock the BOP 42 in a closed configuration in which the BOP 42 blocks a fluid flow through the central bore 44. For example, the cavity lock system may drive a lock member into a cavity (e.g., ram cavity) of the BOP 42 to contact and/or to block movement of a ram of the BOP 42 while the ram is positioned within the central bore 44. In this way, the cavity lock system may lock the ram to thereby lock the BOP 42 in the closed configuration in which the BOP 42 blocks the fluid flow through the central bore 44.

FIGS. 2 and 3 are cross-sectional side views of an embodiment of a BOP 42 that may be used in the system 10 of FIG. 1. In FIG. 2, each ram 50 of the BOP 42 is in a first ram position 52 (e.g., open position). In the first ram position 52, each ram 50 is withdrawn from the central bore 44, enables a fluid flow through the central bore 44, does not contact the conduit 24, and/or does not contact a corresponding opposed ram 50. In FIG. 3, each ram 50 of the BOP 42 is in a second ram position 54 (e.g., closed position). In the second ram position 54, the ram 50 extends into the central bore 44, blocks the fluid flow through the central bore 44, contacts the conduit 24, and/or contacts the corresponding opposed ram 50. While the ram 50 is in the first ram position 52, the BOP 42 may be in an open configuration 56 in which the BOP 42 enables the fluid flow through the central bore 44. While each ram 50 is in the second ram position 54, the BOP 42 may be in a closed configuration 58 in which the BOP 42 blocks the fluid flow through the central bore 44. For example, each ram 50 may include a ram body 60 and a sealing element 62 (e.g., packer), and the sealing elements 62 of the opposed rams 50 may contact and seal against the conduit 24 to thereby seal an annulus about the conduit 24 to block the fluid flow through the central bore 44. It should be appreciated that the rams 50 may be configured to seal the central bore 44 without the conduit 24 (e.g., the sealing elements 62 of the opposed rams 50 may contact and seal against one another to seal the central bore 44).

As shown, the BOP 42 includes a housing 70 that houses each ram 50. In particular, the central bore 44 has a bore central axis 72 (e.g., aligned with the vertical axis 30) and extends through the housing 70. The housing 70 also defines a cavity 74 (e.g., ram cavity) that has a cavity central axis 76 (e.g., aligned with the longitudinal axis 32) and intersects the central bore 44 (e.g., the bore central axis 72 and the cavity central axis 76 are transverse or orthogonal to one another). This configuration enables each ram 50 to move between the first position 52 in which the ram 50 is withdrawn from the central bore 44 and positioned within the cavity 74 to the second position 54 in which the ram 50 is positioned within the central bore 44 and extends from cavity 74.

The housing 70 may also house components of an actuator assembly 80 that drives each ram 50 between the first ram position 52 and the second ram position 54. For example, in the illustrated embodiment, the actuator assembly 80 includes a respective piston 82 and a respective connecting rod 84 for each ram 50. In operation, upon an increase in wellbore pressure or upon another indication that the BOP 42 should be adjusted to the closed configuration 58, a fluid may be provided into a respective piston cavity 86 to drive the respective piston 82, as well as the respective connecting rod 84 and the respective ram 50 coupled thereto, toward the central bore 44. In this way, each ram 50 may be driven from the first ram position 52 of FIG. 2 to the second ram position 54 of FIG. 3. In the illustrated embodiment, the cavity 74 is separate from the piston cavities 86 (e.g., sealed from one another, such as via one or more annular seals), and the cavity 74 houses and circumferentially surrounds the rams 50 and at least a portion of the connecting rods 84 while the rams 50 are in the first ram position 52. The cavity 74 may be open to the central bore 44 and may be exposed to wellbore pressure (e.g., wellbore 26, FIG. 1).

As shown, the BOP 42 may include or be associated with a cavity lock system 90. The cavity lock system 90 may include one or more lock members 92. In the illustrated embodiment, the cavity lock system 90 includes four lock members 92. In particular, the cavity lock system 90 includes two lock members 92 for each ram 50 (e.g., a first lock member and a second lock member positioned on opposite sides of the ram 50 and the cavity 74). However, the cavity lock system 90 may include any number of lock members 92 (e.g., 1, 2, 3, 4, 5, 6, 7, 8 or more) in any of a variety of configurations.

Each lock member 92 is configured to move from a first lock position 94 (e.g., unlocked position or configuration), which is shown in FIG. 2, to a second lock position 96 (e.g., locked position or configuration), which is shown in FIG. 3. In the first lock position 94, the lock member 92 may be withdrawn from the cavity 74, enables the ram 50 to move between the first ram position 52 and the second ram position 54, and/or does not contact the ram 50 and/or the connecting rod 84. In the second lock position 96, the lock member 92 may extend into the cavity 74, blocks movement of the ram 50 between the first ram position 52 and the second ram position 54, and/or contacts the ram 50 and/or the connecting rod 84. In particular, the lock member 92 is configured to block movement of the ram 50 from the second ram position 54 to the first ram position 52 (e.g., the block withdrawal of the ram 50 from the central bore 44), thereby locking the ram 50 in the second ram position 54 to lock the BOP 42 in the closed configuration 58.

The lock members 92 may have any of a variety of configurations (e.g., cross-sectional shapes, sizes, positions) and may move in any of a variety of ways. For example, each lock member 92 may be associated with a lock actuator assembly 98. In some embodiments, the lock actuator assembly 98 may include a lock cavity 100 (e.g., lock cylinder) that houses a piston portion 102 (e.g., drive portion) of the lock member 92. It should be appreciated that the piston portion 102 may have any of a variety of configurations, and may generally include a surface that enables a fluid in the lock cavity 100 to exert a force on the surface to drive the lock member 92. For example, in operation, a fluid (e.g., liquid or gas) may be provided to the lock cavity 100 (e.g., via a fluid conduit 104). The fluid may exert a force on the piston portion 102 of the lock member 92, thereby driving a lock portion 106 (e.g., ram-contacting portion) of the lock member 92 into the cavity 74.

With reference to FIG. 3, a ram-contacting surface 108 (e.g., longitudinally-facing surface) of the lock member 92 may contact a lock-contacting surface 110 (e.g., longitudinally-facing surface) of the ram 50. In the illustrated embodiment, the lock-contacting surface 110 of the ram 50 faces away from the central bore 44 and/or is a rearmost surface of the ram body 60 (e.g., furthest from the central bore 44). However, it should be appreciated that the lock member 92 may be configured to contact and engage another surface of the ram 50, such as a surface of a recess or other corresponding feature formed in the ram body 60. Furthermore, while the illustrated embodiment shows the lock member 92 extending and moving vertically into the cavity 74 (e.g., along the vertical axis 30), it should be appreciated that the lock member 92 may extend and move laterally (e.g., along the lateral axis 34) into the cavity 74. For example, instead of or in addition to being positioned on opposite sides of the ram 50 along the vertical axis 30, the lock members 92 may be positioned on opposite sides of the ram 50 along the lateral axis 34.

The movement of the ram 50 and the movement of the lock member 92 may be coordinated (e.g., via an electronic controller 112). For example, as the ram 50 moves into the central bore 44 and/or after the ram 50 reaches the second ram position 54, the electronic controller 112 may control an actuator to actuate a valve to enable the fluid to flow into the lock cavity 100 to drive the lock member 92 to the second lock position 96 to lock the ram 50 in the second ram position 54. The movement may be coordinated via an automated control process with or without sensor feedback. In some embodiments, the movement may be coordinated using signals from a sensor, such as position signals from a position sensor configured to monitor the position of the ram 50. To account for possible variations in movement between the rams 50 (e.g., the rams 50 may not move simultaneously), a respective position of each ram 50 may be monitored separately, such as by separate position sensors, and then the lock members 92 for each ram 50 may be moved independently at different times based on the respective position of each ram 50). The lock member 92 may be returned to the first lock position 94 via any of a variety of techniques. For example, the lock member 92 may be returned to the first lock position 94 via a fluid being provided to the lock cavity 100 (e.g., via a fluid conduit 114) and/or via a biasing member 116 that biases the lock member 92 toward the first lock position 94. It should be appreciated that the biasing member 116 may be coupled to the lock member 92 in any of a variety of ways and at any of a variety of locations. In this way, the cavity lock system 90 may enable the ram 50 to be withdrawn from the central bore 44 to return to the first ram position 52. In some embodiments, the wellbore pressure may be diverted or utilized to assist the lock actuator assembly 98 to maintain the lock member 92 in the second lock position 96. As shown, various seals 118 (e.g., annular seals) may be provided to seal and/or to isolate certain cavities.

The electronic controller 112 includes a processor 120 and a memory device 122. In some embodiments, the processor 120 may receive and process signals from a sensor that monitors the pressure within the wellbore to determine that the BOP 42 should be adjusted from the open configuration 56 to the closed configuration 58. In some embodiments, the processor 120 may receive other signals (e.g., operator input) that indicate that the BOP 42 should be adjusted from the open configuration 56 to the closed configuration 58. Then, the processor 120 may provide control signals, such as to the actuator assembly 80 to adjust the rams 50 to the second ram position 54 and to the actuator to adjust the valve to enable the fluid to flow into the lock cavity 100, in response to the determination or the indication that the BOP 42 should be adjusted from the open configuration 56 to the closed configuration 58.

The electronic controller 112 may be part of or include a distributed controller or control system with one or more electronic controllers in communication with one another to carry out the various techniques disclosed herein. The processor 120 may also include one or more processors configured to execute software, such as software for processing signals and/or controlling the components associated with the cavity lock system 90 and/or the BOP 42. The memory device 122 disclosed herein may include one or more memory devices (e.g., a volatile memory, such as random access memory [RAM], and/or a nonvolatile memory, such as read-only memory [ROM]) that may store a variety of information and may be used for various purposes. For example, the memory device 122 may store processor-executable instructions (e.g., firmware or software) for the processor 120 to execute, such as instructions for processing signals and/or controlling the components associated with the cavity lock system 90 and/or the BOP 42. It should be appreciated that the electronic controller 112 may include various other components, such as a communication device 124 that is capable of communicating data or other information to various other devices (e.g., a remote computing system).

FIGS. 4-11 illustrate various embodiments and features that may be used in the cavity lock system 90. For example, FIGS. 4 and 5 are cross-sectional side views of a portion of an embodiment of the BOP 42 that may be used in the system 10 of FIG. 1, wherein the lock member 92 is maintained in the first lock position 94 due to engagement with the ram 50 and the lock member 92 is biased toward the second lock position 96 via a biasing member 140 (e.g., spring). It should be appreciated that the biasing member 140 may be coupled to the lock member 92 in any of a variety of ways and at any of a variety of locations.

In particular, in FIG. 4, the ram 50 is in the first ram position 52 and the lock member 92 is in the first lock position 94. In FIG. 5, the ram 50 is in the second ram position 54 and the lock member 92 is in the second lock position 96. As shown, while the ram 50 is in the first ram position 52, the ram 50 maintains the lock member 92 in the first lock position 94 (e.g., holds the lock member 92 in the first lock position 94 against the bias of the biasing member 140) and blocks the lock member 92 from moving to the second lock position 96. For example, a lock-holding surface 142 (e.g., vertically-facing surface; upper surface; lock-contacting surface) of the ram 50 may contact a ram-contacting surface 144 (e.g., vertically-facing surface; lower surface) of the lock member 92.

In operation, as the ram 50 is driven into the central bore 44, the loss of contact between the opposed surfaces 142, 144 may enable the biasing member 140 to drive the lock member 92 from the first lock position 94 to the second lock position 96. Then, the ram-contacting surface 108 of the lock member 92 may contact the lock-contacting surface 110 of the ram 50. In this way, the cavity lock system 90 may automatically adjust the lock member 92 into the second lock position 96 to lock the ram 50 into the second ram position 54 in response to the ram 50 being driven into the central bore 44 and/or reaching the second ram position 54.

The lock member 92 may be returned to the first lock position 94 via any of a variety of techniques. For example, the lock member 92 may be positioned within a lock cavity 146 (e.g., lock cylinder) and may be returned to the first lock position 94 via a fluid being provided to the lock cavity 146 (e.g., via a fluid conduit 148) to overcome the bias of the biasing member 140. Then, the ram 50 may be withdrawn from the central bore 44 to return to the first ram position 52.

FIGS. 6 and 7 are cross-sectional side views of a portion of an embodiment of the BOP 42 that may be used in the system 10 of FIG. 1, wherein the lock member 92 is configured to rotate between the first lock position 94 and the second lock position 96. In particular, in FIG. 6, the ram 50 is in the first ram position 52 and the lock member 92 is in the first lock position 94. In FIG. 7, the ram 50 is in the second ram position 54 and the lock member 92 is in the second lock position 96.

As shown, while the lock member 92 is in the first lock position 94, the lock portion 106 of the lock member 92 may be positioned outside of the cavity 74 and/or does not contact the ram 50. In operation, as the ram 50 is driven into the central bore 44 or after the ram 50 reaches the second ram position 54, the lock member 92 may be driven to rotate about a pivot 150 in a direction 152 until the lock portion 106 is positioned within the cavity 74, contacts the ram 50, and/or locks the ram 50 in the second ram position 54 (e.g., blocks withdrawal of the ram 50 from the central bore 44). The lock member 92 may be driven to rotate in any of a variety of ways, such as via a motor that drives rotation of a shaft (e.g., output shaft) that is coupled to (e.g., fixed to; non-rotatably coupled to) the lock member 92.

The lock member 92 may be returned to the first lock position 94 via any of a variety of techniques. For example, the lock member 92 may be returned to the first lock position 94 by rotating the lock member 92 about the pivot 150 in a direction opposite the direction 152, such as via the motor that drives rotation of the shaft that is coupled to the lock member 92. Then, the ram 50 may be withdrawn from the central bore 44 to return to the first ram position 52.

FIG. 8 is a cross-sectional side view of an embodiment of a portion of the BOP 42, wherein the lock member 92 is configured to move at a non-perpendicular angle relative to the ram 50. For example, the lock member 92 may be configured to move in a direction 160, which enables the lock member 92 to exert a force against the ram 50 to drive the ram 50 toward the central bore 44, thereby increasing the effectiveness of the seal of the central bore 44. In some embodiments, the lock member 92 may be driven along the vertical axis 30 and then along the longitudinal axis 32 against the ram 50 to enable the lock member 92 to exert the force against the ram 50.

FIG. 9 is a cross-sectional side view of an embodiment of a portion of the BOP 42, wherein the lock member 92 has a wedge shape (e.g., cross-sectional shape). For example, at least the ram-contacting surface 108 of the lock member 92 may be tapered (e.g., along the vertical axis 30). The wedge shape may enable the lock member 92 to be used with various different types of rams 50 (e.g., having different shapes or configurations) and/or rams 50 having different positions while in the second ram position 54 (e.g., due to variations in a volume of the packer 62, which may be from wear over time, and/or due to manufacturing variations). For example, the wedge shape may contact one type of ram 50 at one location of the ram-contacting surface 108 of the wedge shape to lock the ram 50 in the second ram position 54, and the wedge shape may contact another type of ram 50 at another location of the ram-contacting surface 108 of the wedge shape to lock the ram 50 in the second ram position 54. The wedge shape may enable the lock member 92 to exert a force against the ram 50 to drive the ram 50 toward the central bore 44, thereby increasing the effectiveness of the seal of the central bore 44. Similarly, FIG. 10 is a cross-sectional side view of an embodiment of a portion of the BOP 42, wherein the lock member 92 has a wedge shape and the ram 50 has a corresponding wedge shape (e.g., the ram-contacting surface 108 and the lock-contacting surface 110 have corresponding wedge shapes and taper in opposite directions along the vertical axis 30).

FIG. 11 is a cross-sectional side view of an embodiment of a portion of the BOP 42, wherein the lock member 92 is configured to engage the connecting rod 84 to block withdrawal of the ram 50 from the central bore 44. As shown, the lock member 92 is configured to engage a recess 170 formed in a surface 172 (e.g., radially-outer surface) of the connecting rod 84. The lock member 92 may have any of a variety of shapes and may be configured to move in any of the manners described above with respect to FIGS. 2-10 to engage the connecting rod 84, for example.

FIG. 12 is a flow chart illustrating a method 180 for using the cavity lock system 90, in accordance with the present disclosure. The method 180 includes various steps represented by blocks. It should be noted that the method 180 may be performed as an automated procedure by a system, such as the electronic controller 112. Although the flow chart illustrates the steps in a certain sequence, it should be understood that the steps may be performed in any suitable order and certain steps may be carried out simultaneously, where appropriate. Further, certain steps or portions of the method 180 may be performed by separate devices. As noted above, the steps for using the cavity lock system 90 may be initiated automatically (e.g., following a signal that indicates that the BOP 42 should be adjusted to the closed configuration 58 and/or following a signal that indicates that the ram 50 of the BOP 42 is in the second ram position 54).

As shown, in step 182, the electronic controller 112 may provide a drive signal to cause the ram 50 to move from the first ram position 52 to the second ram position 54. In step 184, the electronic controller 112 may provide a drive signal to cause the lock member 92 to contact the ram 50 to lock the ram 50 in the second ram position 54 (e.g., to block withdrawal of the ram 50 from the central bore 44. For example, with reference to FIGS. 2 and 3, the electronic controller 112 may instruct the actuator to adjust the valve to enable the fluid flow into the lock cavity 100 via the fluid conduit 104 to drive the lock member 92 to the second lock position 96. With reference to FIGS. 6 and 7, the electronic controller 112 may instruct the motor to drive rotation of the lock member 92 about the pivot 150 to reach the second lock position 96. Step 184 may be carried out at the same time as step 182 and/or after step 182 (e.g., as the ram 50 moves toward the second ram position 54 and/or after the ram 50 reaches the second ram position 54).

In step 186, the electronic controller 112 may provide a drive signal to cause the lock member 92 to separate from the ram 50 to enable withdrawal of the ram 50 from the central bore 44. For example, with reference to FIGS. 2 and 3, the electronic controller 112 may instruct the actuator to adjust the valve to enable the fluid flow into the lock cavity 100 via the fluid conduit 114 to drive the lock member 92 to the first lock position 94. With reference to FIGS. 4 and 5, the electronic controller 112 may instruct the actuator to adjust the valve to enable the fluid flow into the lock cavity 146 via the fluid conduit 148 to drive the lock member 92 to the first lock position 94. With reference to FIGS. 6 and 7, the electronic controller 112 may instruct the motor to drive rotation of the lock member 92 about the pivot 150 to reach the first lock position 94.

In step 188, the electronic controller 112 may provide a drive signal to cause the ram 50 to move from the second ram position 54 to the first ram position 52. Step 188 may be carried out at the same time as step 186 and/or after step 186 (e.g., as the lock member 92 moves toward the first lock position 94 and/or after the lock member 92 reaches the first lock position 94). As noted above, instead of drive signals from the electronic controller 112, some embodiments may utilize one or more biasing members (e.g., biasing member 116, 140) to drive the lock member 92. Furthermore, instead of contacting the ram 50, the lock member 92 may contact and engage the connecting rod 84.

It should be appreciated that any of the features illustrated and described with respect to FIGS. 1-12 may be combined in any suitable manner. As a non-limiting example, the lock member 92 of FIGS. 4 and 5 may have the cross-sectional shape shown in FIG. 8 or 9 (e.g., no separate piston portion 102 and the biasing member 116, 140 may return the lock member 92 to the first lock position 94). Furthermore, as noted above, the wellbore pressure may be diverted or utilized to assist the cavity lock system 90 to maintain the lock member 92 in the second lock position 96. Furthermore, the BOP 42 may include opposed rams 50 and/or any suitable number of lock members 92. Additionally, the electronic controller 112 may control the various disclosed operations of the BOP 42, including the various disclosed operations of the cavity lock system 90. However, in some embodiments, the rams 50 and/or the lock members 92 may be manually actuated (e.g., by an operator). The cavity lock system 90 disclosed herein may be used in conjunction with other types of lock systems, such as lock systems that include lock members that contact and engage a portion of the actuator assembly 80 (e.g., an actuator rod that drives the piston 82) to lock the ram 50 within the central bore 44.

While the disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the following appended claims.

The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f). 

1. A blowout preventer (BOP), comprising: a ram supported within a cavity that is positioned crosswise to a central bore of the BOP, wherein the ram is configured to move within the cavity between an open position in which the ram is withdrawn from the central bore and a closed position in which the ram is positioned within the central bore to thereby block a fluid flow through the central bore; and a lock member configured to move between an unlocked position and a locked position in which the lock member is positioned within the cavity of the BOP to thereby lock the ram in the closed position.
 2. The BOP of claim 1, comprising an electronic controller configured to coordinate movement of the ram and the lock member, such that the lock member moves toward the locked position as the ram moves toward the closed position, after the ram reaches the closed position, or both.
 3. The BOP of claim 1, comprising a biasing member configured to bias the lock member toward the locked position.
 4. The BOP of claim 3, wherein the ram is configured to contact the lock member to thereby block the biasing member from driving the lock member to the locked position, while the ram is in the open position.
 5. The BOP of claim 1, wherein the lock member comprises a wedge shape.
 6. The BOP of claim 1, wherein the lock member is configured to rotate relative to the ram to move to the locked position.
 7. The BOP of claim 1, wherein the lock member is withdrawn from the cavity while the lock member is in the unlocked position.
 8. The BOP of claim 1, comprising an additional lock member configured to move between a respective unlocked position and a respective locked position in which the additional lock member is positioned within the cavity of the BOP and contacts the ram to thereby lock the ram in the closed position.
 9. The BOP of claim 8, wherein the lock member and the additional lock member are positioned on opposite sides of the cavity.
 10. The BOP of claim 1, wherein the lock member is configured to contact the ram while the lock member is in the locked position and while the ram is in the closed position.
 11. A cavity lock system for a blowout preventer (BOP), comprising: a lock member configured to move between an unlocked position and a locked position in which the lock member is positioned within a cavity of the BOP to enable the lock member to contact a ram of the BOP to thereby block withdrawal of the ram from a central bore of the BOP.
 12. The cavity lock system of claim 11, comprising an electronic controller configured to coordinate movement of the ram and the lock member, such that the lock member moves toward the locked position as the ram moves toward a closed position in which the ram seals the central bore, after the ram reaches the closed position, or both.
 13. The cavity lock system of claim 11, comprising a biasing member configured to bias the lock member.
 14. The cavity lock system of claim 11, comprising a hydraulic system configured to drive the lock member to the locked position, the unlocked position, or both.
 15. The cavity lock system of claim 14, wherein the hydraulic system comprises a lock cavity, the lock member comprises a piston portion positioned within the lock cavity, and the hydraulic system is configured to provide a fluid into the lock cavity to exert a force on the piston portion to drive the lock member to the locked position or to the unlocked position.
 16. The cavity lock system of claim 11, wherein the lock member comprises a wedge shape.
 17. A method of operating a cavity lock system for a blowout preventer (BOP), comprising: adjusting a ram from an open position in which a body of the ram is withdrawn from a central bore of the BOP to a closed position in which the body of the ram is positioned within the central bore of the BOP to thereby block a fluid flow through the central bore of the BOP; and adjusting a lock member to contact the body of the ram while the ram is in the closed position to thereby lock the ram in the closed position.
 18. The method of claim 17, wherein adjusting the lock member comprises driving the lock member via a biasing member that biases the lock member into a cavity of the BOP.
 19. The method of claim 18, comprising maintaining the lock member in an unlocked position due to engagement between the ram and the lock member that overcomes a bias of the biasing member, while the ram is in the open position.
 20. The method of claim 17, wherein adjusting the lock member comprises providing a hydraulic fluid to drive the lock member into a cavity of the BOP. 